6.9
Summary

Among the options available in I/O cells are: different drive strengths, TTL-compatibility, registered or direct inputs, registered or direct outputs, pull-up resistors, over-voltage protection, slew-rate control, and boundary-scan.
Table 6.4
shows a list of features. Interfacing an ASIC with a system starts at the outputs where you check the voltage levels first, then the current levels.
Table 6.5
is a look-up table for Tables
6.6
and
6.7
, which show the I/O resources present in each type of programmable ASIC (using the abbreviations of
Table 6.4
).